[RFC] iio: magnetometer: mlx90393 - regmap vs command-based access

[RFC] iio: magnetometer: mlx90393 - regmap vs command-based access

[Nikhil Gautam]

Hi,

I am working on adding support for the MLX90393 magnetometer.

The device uses a command-based protocol (e.g. SM, RM, RR)
rather than a traditional register map.

Before proceeding, I wanted to clarify the preferred design:

- Should regmap be used in such cases, even without a linear
  register map?

- Or is it acceptable to implement a custom command-based
  abstraction layer?

My understanding is that regmap may not be a good fit here,
but I would appreciate guidance before implementing.

Also, pointers to similar IIO drivers would be helpful.

Thanks,
Nikhil Gautam

Re: [RFC] iio: magnetometer: mlx90393 - regmap vs command-based access

[Nikhil Gautam]

Hi,

Apologies for missing a few details in the previous mail.

The MLX90393 supports both I2C and SPI interfaces.

Commands include, for example:
- SM (Start Measurement)
- RM (Read Measurement)
- RR (Read Register)

Given this command-oriented interface over both I2C and SPI,
I wanted to confirm whether a custom command abstraction layer
would still be the preferred approach instead of regmap.

Thanks,
Nikhil Gautam

Re: [RFC] iio: magnetometer: mlx90393 - regmap vs command-based access

[Andy Shevchenko]

On Thu, Apr 23, 2026 at 05:55:35PM +0530, Nikhil Gautam wrote:
> 
> Apologies for missing a few details in the previous mail.
> 
> The MLX90393 supports both I2C and SPI interfaces.
> 
> Commands include, for example:
> - SM (Start Measurement)
> - RM (Read Measurement)
> - RR (Read Register)
> 
> Given this command-oriented interface over both I2C and SPI,
> I wanted to confirm whether a custom command abstraction layer
> would still be the preferred approach instead of regmap.

I found only 4 drivers for this vendor in the kernel and they seem
either register based or eeprom based. Perhaps the latter is the
case here? Have you checked existing implementations?

-- 
With Best Regards,
Andy Shevchenko